"Be vocal," one French envoy advises, "even more so if the Iranians ask you not to be, because silence will not expedite the process."

Some of the documents also reveal a diplomatic struggle with Pakistan over nuclear proliferation -- a disagreement that Hoekstra said had no business in the public sphere.

"Bottom line here is we want to work with the Pakistanis on proliferation. Putting the negotiations, the agreements and the disagreements that we have with our allies, putting them in the public spotlight is going to make it more difficult for us to get to the ultimate objective, which is to stop the proliferation of nuclear weapons," he said. "Wikileaks is not providing us a service."

Beyond policy concerns, the White House said that the leak puts individuals in danger.

"Such disclosures put at risk our diplomats, intelligence professionals and people around the world who come to the United States for assistance in promoting democracy and open government," the White House said in a statement Sunday.

One official told ABC News that the administration is concerned over cables that contain the name of foreign dissidents who could now be in danger in their home countries.

"These people will disappear," the official said.

The source of the leak is believed to be former military intelligence analyst Bradley Manning, who was arrested in July for distributing classified information. Authorities also believe Manning was behind a previous Wikileaks document drop, referred to as the Iraq War Logs.

This latest leak, seven times the size of the Iraq War Logs, amounts to "the Sept. 11 of world diplomacy," according to Italian Foreign Minister Franco Frattini. Hoekstra said it reflected a "colossal failure" by the U.S. intelligence community.

"We have to take a look at our own intel community and recognize that this is a massive failure. This database should never have been created, hundreds of thousands of people should never have been given access to it," Hoekstra said. "This is a colossal failure by our intel community, by our Department of Defense to keep classified information secret."

Assange has given hints of what is still to come from Wikileaks, claiming in a statement the U.S. spies on its allies, turns a "blind eye" to corruption and human rights abuse and "makes backroom deals with supposedly neutral countries and lobbying for U.S. corporations."